Hi Keith, sorry I only have an AD model. That has what looks like a bigger door. But it's still not easy to lift out without a handle on the battery.
The actual battery box bolts onto the chassis on mine but you probably need the battery out to remove it.
Hard to imagine they built them without a serviceable battery access.

If you want to change yours the AD lid is a cheap repro available all over.

I think I am going to make a cut where that dip is in the floor pan and then make that into a door and screw it in. That way there is plenty of room to access the battery. The way it is you cannot even remove the cables. Got some pictures today, but will post them tomorrow as it is time to get to bed.

Wow...not a very friendly design. Bel Air kiwi mentioned the access door in the Advanced Design 47-55 trucks. It does offer a lot more room to do everything that you'd need to do with the battery to include installation and removal. If you had room to install that in your truck it would make a much nicer alteration. My battery access door measures 9 1/4" X 12 1/2". It would be a matter of cutting the opening out of one of the AD trucks and welding it into your floor...IF room allows.

I had some folks on another site said to leave it stock. I figured I could make one cut across it and then us the cut piece to make a screw in door. I did see on utube, a 46 with a battery box under the hood on the firewall, drivers side. I don't have access to my pickup right now, but will check it our.

I am one of those "stock" guys too so I understand folks saying that. Another alternative would be fabricating or finding a separate floor, putting an access whole and lid in that one and keeping the original floor. There is an original on eBay now...[see below]... and they seem to make re-pops of these as well. I know! I know! A simple fix is getting more and more expensive!